Hydraulic ram mechanism having shielding and stop means



June 20, 1950 v. E. GEREN 2,512,150 mmuwuc m MECHANISM mwmc sumwmc ANDSTOP MEANS Filed Jan. 8, 1947 I 2 Sheets-Sheet 1 fi-i a J8 IN V EN TOR.

VINCENT E. GEREN Agent June 20, 1950 v. E. GEREN HYDRAULIC RAM MECHANISMHAVING sumwmc AND STOP MEANS 2 Sheets-Sheet 2 Filed Jan. 8, 1947INVENTOR.

VINCENT E. GEREN Agent 7/4 VIII/Ill/lll ELI: n

Patented June 20, 1950 HYDRAULIC RAM MECHANISM HAVING SHIELDING AND STOPMEANS Vincent E. Geren, Los Angeles, Calif., assignor to AirquipmentCompany, Burbank, Calif.

Application January 8, 1947, Serial No. 720,857

Claims. 1

This invention relates to hydraulic ram mechanisms, and relates moreparticularly to mechanisms of this character employed to operateextensible stands used in the servicing of airplanes. passenger loadingramps for airplanes, etc.

The servicing of airplanes requires the use of elevated stages or standswhich must be capable of vertical adjustment to allow the workmen toservice the various parts of aircraft of diflerent types and models.Other equipment used in connection with modern airplanes alsonecessitate vertical extension and contraction. For example, passengerloading ramps are often constructed for ready vertical adjustment toadapt them for use with various airplanes. Hydraulic ram mechanisms areusually incorporated in such devices to obtain the desired adjustments.Equipment of the class referred to is exposed to the weather, and thepiston rods of the hydraulic actuating mechanisms are subjected tocorrosion by the elements. This results in wear and damage to the rampiston rod and its bearings.

There is always the possibility that the extensible airplane servicingequipment will collapse as a result of hydraulic pressure failure, andit is customary to provide a safety lock to prevent such unintentionallowering of the equipment. The safety lock usually employed consists ofa pin inserted through one of a plurality of transverse openings in thepiston rod so as to bear against the upper end of the cylinder. The lockpin only looks the mechanism against movement in one direction; that is,against downward travel, and cannot prevent upward extension in theevent excess hydraulic pressure is inadvertently applied to the ram.Furthermore, the transverse openings in the piston rod carry water anddirt into the cylinder when the mechanism is operated.

It is a general object of this invention to provide a ram mechanism ofthe general class above referred to which incorporates simple,efl'ective means for protecting the ram piston rod and its bearingsagainst corrosion and the eflects of the elements. Heretofore the onlyprotection provided for these parts was paint or grease, which quicklylost their protective abilities. The mechanism of this inventionprovides permanent and substantially complete protection for the pistonrod and its bearings, thus insuring a longer life for the mechanism.

Another important object of the invention is to provide a ram mechanismof the type referred to embodying safety lock means adapted todependably lock the ram mechanism against both upward extension anddownward contraction in any selected position The safety means of the 2invention is positive and dependable, insuring retention of theequipment at the selected elevation, even though the actuating hydraulicpressure is inadvertentlyeither increased or decreased.

Another object of the invention is to provide a mechanism of thecharacter referred to in which the safety lock means does notnecessitate the provision of spaced openings in the piston rod or othersurfaces or parts which might carry water and foreign material into thecylinder. The safety means is associated with the piston rod shieldingassembly and is independent of the portion of the piston rod whichenters the cylinder.

Another object of the invention is to provide a hydraulic ram mechanismin which the safety lock means may either be directly manually engagedand released, or constructed for remote manual control.

A further object of the invention is to provide a piston rod shieldingmeans and safety lock means that may be conveniently embodied in orapplied to the hydraulic ram mechanism without materially modifying oraltering the'same.

Other objects and features of the invention will be readily understoodfrom the following detailed description of typical preferred forms ofthe invention wherein reference will be made to the accompanyingdrawings in which:

Figure 1 is a side elevation of an adjustable work stand embodying thepresent invention;

Figure 2 is a diagrammatic view of the fluid pressure system of theapparatus;

Figure 3 is an enlarged longitudinal detailed sectional view of thelower portion of the ram mechanism with certain parts appearing in sideelevation;

Figure 4 is an enlarged longitudinal detailed sectional view of theupper portion of the ram mechanism;

Figure 5 is a reduced perspective view of the ram mechanism showing oneform of locking device associated therewith; and,

Figure 6 is a fragmentary perspective view of the ram mechanismillustrating another form of locking device. 4

The present invention is capable of embodiment in and application tohydraulic ram mechanisms intended for the actuation of various types ofdevices and equipment. In the drawings I have shown the ram mechanismincorporated in an extensible stand or staging useful in theconstruction and servicing of airplanes. It is to be understood thatthis is merely one typical application and is not to be construed asrestrictive of the use of the invention.

cates with the interior of the cylinder 20.

The extensible stand illustrated includes a wheeled base I comprised oflongitudinal and transverse members secured together to form arectangular frame. The frame or base II is carried by wheels equippedwith suitable tires. A pivotally supported ladder or step structure I2,is mounted on the base Ill and carries a horizontal work platform 13.The step structure includes two pairs of upright side members l4 and I5pivoted at their lower ends to plates IS on the base H). The upper endsof the four members H and I5 are pivoted to the horizontal platform I3.The pivotal axes of the members l4 and 15 are such that the membersremain parallel at all times, and the platform |3 remains parallel withthe base It. Suitable spaced steps ll extend between and are pivotallyconnected to the side members l4 and I5 to provide free access to theplatform l3. The parallel relationship of the members H and |5 holds 20the steps ll horizontal in all elevations of the platform. A guard railI8 is provided for platform 13 and suitable rails l9 are associated withthe ladder or step assembly. It is to be understood that the work standmay include other features, but these are omitted from the presentdisclosure as being unnecessary to a iull understanding of theinvention.

The features of the present invention are incorporated in a hydraulicram mechanism for raising and lowering the platform l3. This mechanismincludes an elongate cylinder 20 provided at its lower end with a plugor cap 2|. The cylinder cap 2| is pivoted on a cross member 22mechanism. This extends a considerable portion of the piston rod 26 fromthe upper end of the cylinder 20. The protective shield means of theinvention effectively guards the extended portion of the piston rod 26against the action of the elements and against the accumulation of dirt.The protective means includes an elongate sleeve &3 secured to the upperend portion of the rod 26. In the construction illustrated, a tubularblock or spacer 44 is arranged in the upper portion of the sleeve, andone or more bolts 45 pass through transverse openings in the sleeve 43,-spacer 44 and rod 26 to secure the sleeve to the rod. The upper portionof the sleeve 43 which contains the spacer 44, may be reinforced by anexternal collar 4B. The protective sleeve 43 surrounds the piston rod 26in spaced concentric relation thereto and is of sufilcient diameter totelescope over the cylinder with substantial clearance. The sleeve 43 isalso sufficiently long to extend downwardly over a considerable portionof the cylinder 20, even when the piston rod is in its uppermost orfully extended position. The shielding portion of the sleeve 43; thatis, the major portion of the sleeve extending downwardly from the spacer44 and telescoping over the cylinder 20, is

imperforate or fully closed to completely exclude of the base It by apin 23 passing through horizontal openings in the cap and lugs 24 on thecross member. A plunger 25 operates in the cylinder 20 and has a pistonrod 25 extending upwardly and outwardly from the cylinder. The lowerportion of the plunger 25 carries a suitable sealing ring assembly 21for slidably sealing with the cylinder 20, and the plunger has a bearingsurface adjacent the packing ring assembly for engaging with thecylinder wall. The piston rod 26 slidably passes through a bearing 28 inthe upper end of the cylinder 20 and its projecting upper end ispivotally connected with the platform I3. In the drawings I have shownthe upper end of the piston rod pivoted at 30 to a stabilizing assembly3| depending from the platform 13. I

Figure 5 illustrates in a diagrammatic manner the system for supphringthe actuating fluid pressure to the cylinder 20. This system includes apump 32 mounted on the base In and operated by a hand lever 33. A line34 leads from a liquid reservoir 35 to the inlet of the pump 32, beingcontrolled at the pump by a check valve 38. A pressure line 31 extendsfrom a check valve 38 at the outlet of the pump to the cap 2| of thecylinder 20 where it communicates with a port 39. The port 39 in turncommuni- A by-pass pipe 40 connects the-twolines 34 and 31 and iscontrolled by a manually operable valve 4|. It will be seen that withthe valve 4| closed, operation of the pump 32 supplies fluid underpressure to the cylinder 20 to elevate the step assembly l2 and platforml3. The valve 4| may be subsequently opened to allow the stand to lower.By suitable manipulation of the pump 32 and valve 4|, the platform l3may be brought to any required position.

The platform l3 may be operated to a substantial elevation by the abovedescribed ram 7 41 and spacers 48.

water, dirt, dust,-etc. As will be later described, the protectivesleeve 43 is centered and slidably guided on the cylinder 2|) byelements of the safety lock means.

The lock means of the invention includes a plurality of stop or lockmembers longitudinally spaced along the exterior of the cylinder 20. Inthe preferred construction these members are in the form of rings 41surrounding the cylinder 20 at longitudinally spaced points. The rings4'! rather accurately fit around the cylinder 20 and their peripheriesare cylindrical to form spaced guides and bearings for the sleeve 43.Figures 3 and 4 illustrate the manner in which the inner surface of thesleeve 43 slidably rides on the peripheries of the rings 41 to supportand guide the sleeve. The retaining rings 41 are spaced alongsubstantially the entire length of the cylinder 20 by interveningtubular spacers 48. The spacers 48 may be simple tubular members engagedaround the cylinder 20 between the successive rings 41. The lowermostspacer 48 which may be of greater length than the other spacers, mayeither rest on the cap 2| or may be welded on the cylinder 20, or both.The other spacers 48 and the retainer rings 41 may be simpl stacked onthe cylinders 20 in superimposed relation; or if desired, may beindividually secured to the cylinder as by welding. A collar 50 issecured to the upper end of the cylinder 20 by screws 5| or the like, toprevent upward displacement of the rings A series of shims 52 is engagedbetween the upper spacer 48 and the collar 5|! to compensate formanufacturing tolerances in building up the series of rings and spacers.The shims 52 may serve as the uppermost stop or retainer ring of thelock means. It will be observed that the series of rings 41 slidablycooperating with the interior of the protective sleeve 43 excludemoisture and dirt from the interior of the sleeve, and in addition,constitute bearings for the sleeve as above described.

The lock means further includes a locking element 54. adapted to beengaged on the lower portion of the sleeve 43 to cooperate with theadjacent stop rings' 41. The lower portion of the sleeve 43 is externallreinforced by a collar 55 welded or otherwise fixed on the sleeve. The

- thickened or reinforced lower portion of, the sleeve 43 is providedwith two vertically spaced pairs of slots 56 to receive the lockelement, The slots 56 of each pair are horizontal or normal to thelongitudinal axis of the ram assembly, and are formed in diametricallyopposite sides of the sleeve. The lock element 54 is substantially U-shaped in plan view, having a pair of spaced parallel arms 51 joined atone end. The opposite ends of the arms 51 are bevelled at their innercorners to be readily entered in the slots 56. The arms 51 of the lockelement are proportioned to fit the slots 56 and to project into theinterior of the sleeve 43 when engaged in the slots. The arms 51 engagedin a pair of slots 56 are in the path of the adjacent retainer rings 41and upon engaging a ring 41, stop the travel of the sleeve 43 and pistonrod 26 relative to the cylinder 20. Thus the arms 51 of the lockingdevice 56 prevent any substantial movement of the platform l3 in theevent the hydraulic pressure in the cylinder is either increased orreduced subsequent to locking the apparatus at the selected elevation. Ahandle or ring 58 is provided on the locking element 54 to facilitateits manipulation. Where the locking element 54 is a simple manuallyinserted device, as shown in Figures 3 and 5, it is preferred to providetwo vertically spaced pairs of slots 56 so that in the event theplatform i3 is stopped in a selected position where a retainer ring Mprevents introduction of the arms 51 into one pair of slots, the otherpair of slots is unobstructed to receive the locking arms. The pairs ofslots 56 have a different spacing than the rings ti so that one pair ofslots is available to receive the locking device 56 at all times.

Figure 6 illustrates a remotely controllable locking device 60. In thisform of the invention, only one pair of slots 55 is required in the wallof the sleeve 53. In all other respects the sleeve 33, lock rings 4?,spacers tit, etc., are the same as described above. The locking devicetil comprises a pair of crossed levers Bl pivoted between spaced lugs 62on the reinforcing collar 55. Each lever M has an arm 53 for engaging ina slot 55 so as to cooperate with the retainer rings ii. A spring (it isengaged between the outer arms oi the crossed levers iii to yieldinglyurge the levers to positions where the arms 53 are adapted to cooperatewith the rings 41. Remotely controllable or operable means is providedfor pivoting the levers M to withdraw their arms 63 from the slots 55.This means includes a cable 55 connected with the two levers 6i. 1 haveshown the cable 55 attached to inturned fingers or links 58 on the outerarms of the levers. The cable 55 may extend to any selected convenientlyaccessible operating point. When it is desired to release the lockingdevice til to permit free exten sion or contraction of the work stand,the cable 65 is pulled. This swings the lever arms 63 out of the slots56 and therefore out of alignment with the stop rings 41. At all othertimes the spring 64 holds the arms 63 in position in the slots 56 toeffectively prevent movement of the piston rod 26 and platform I3. Evenin the event the platform 13 and piston rod 26 are stopped in a positionwhere a retainer ring 41 is directly opposite the slots 55, anysubsequent movement of the piston rod in either direction moves the ringout of alignment with the slots to allow the lever arms 63 toautomatically move into the active positions where they prevent anyfurther appreciable movement of the platform l3.

It is believed that the operation of the apparatus will be readilyunderstood from the foregoing detailed description. To raise theplatform I! the pump 32 is operated to supply fluid under pressure tothe cylinder 20. This operation is terminated when the platform l3 hasreached the required position. The locking element 54 of Figure 5, isthen arranged so that its arms 51 fit a pair of slots 56. As abovedescribed, the arms I! enter the sleeve 43 to be in the space betweenthe adjacent pair of retainer rings 41. Accordingly, the arms 51 are inposition to prevent either upward or downward displacement of theplatform ii in the event the fluid pressure in the cylinder 20 isinadvertently increased or decreased. Where the automatic lock device 6.of Figure 6 is employed, the lever arms 63 are retracted from theinterior of the sleeve 43 during intended elevation and depression ofthe platform l3. Thisis accomplished by merely imposing a pull on thecable 65. When th platform l3 has reached the selected position, thecable is released, allowing the spring 64 to move the lever arms 63 intothe active positions in alignment with the adjacent retainer rings 41.

The closed protective sleeve 43 secured to the upper end of the pistonrod 26 and telescoping downwardly over the cylinder 20 effectivelyshields the projected portion of the piston rod 25. The sleeve 43prevents water, dust and dirt from reaching the piston rod and itsbearings. As a result, repeated operation of the ram mechanism does notcarry water and foreign matter into the cylinder to corrode and wear theworking parts and bearings. This materiallylengthens the active life ofthe ram mechanism.

Having described only typical forms of th invention, I do not wish to belimited to the specific details herein set forth, but wish to reserve tomyself any variations or modifications that may appear to those skilledin the art and/or fall within the scope of the following claims.

I claim:

1. In a mechanism of the class described the combination of; a cylinder,a piston operabl in. the cylinder and having a rod extending from an endof the cylinder, a sleeve secured to the extending portion of the rodand extending over the cylinder in surrounding relation thereto toprotect the same, axially spaced projections on th exterior of thecylinder slidably engaged by the interior of the sleeve to constitutebearings for the sleeve, and a part on the sleeve cooperable with saidprojections to limit relative axial movement between the cylinder andthe piston.

2. In a mechanism of the class described the combination of; a cylinder,a piston operable in the cylinder and having a rod extending from an endof 'the cylinder, a sleeve secured to the extending portion of the rodand extending over the cylinder in surrounding relation thereto toprotect the same, axially spaced annular pro- Jections on the exteriorof the cylinder slidably engaged by the internal surface of the sleeveto form guide bearings for the sleeve, and an element on the sleeveprojectable thereinto to be engageable with said projections to preventrelative axial movement between the cylinder and piston. I

3. A ram mechanism comprising two parts related for relativelongitudinal movement, on a cylinder, the other a piston operable in thecylinder, a rod on the piston extending from an end of the cylinder, asleeve attached to the rod to enclose the projecting portion of the sameand to telescope over the cylinder, longitudinally spaced stops on thcylinder, an end portion of the sleeve having a pair of longitudinallyspaced slots, and an element engageable in a selected slot andcooperable with said'stops to limit relative movement between thecylinder and piston in both directions.

4. In a ram mechanism th combination 01'; a cylinder, longitudinallyspaced annular projections on the exterior of the cylinder, a pistonoperable in the cylinder, a rod on the piston projecting from an end ofthe cylinder, a sleeve secured to the rod to enclose the projectingportion of the same and telescoping over the cylinder to be slidablyguided by said projections, said annular projections serving to preventthe entrance of foreign matter into the sleeve, and a locking device onthe sleeve for projecting into the space between spaced adjacent annularprojections to be cooperable with said adjacent projections to limitrelative longitudinal movement between the cylinder and piston.

5. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a piston operable inthe cylinder, a rod on the piston extending from an end of the cylinder,a sleeve attached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, stop rings on the exterior ofthe cylinder forming bearings for the sleeve, spacers holding the ringsin spaced apart relation, and a locking device on the sleeve forprojecting into the space between spaced adjacent rings to limit therelative movement between the. cylinder and piston.

6. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a piston operable inthe cylinder, a rod on the piston extending from an end of the cylinder,a sleeve attached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, the sleeve having a slot,longitudinally spaced rings on the exterior oi the cylinder engaged byand forming bearings for the sleeve, and means for preventingappreciable relative movement between the cylinder and piston with therod in any selected position comprising a lock element for engaging insaid slot to extend into the space between two adjacent rings.

7. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a. piston operable inthe cylinder, a rod on the piston extending from an end of the cylinder,a sleeve attached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, the sleeve having a pair ofsubstantially diametrically opposite slots, longitudinally spaced ringson the exterior oi the cylinder slidably engaged by the internal surfaceof the sleeve to form bearings for the sleeve, and means for limitingrelative movement between the cylinder and piston when the same are in aselected relative relationship comprising a lock element having arms forentering said slots to project into the space between a pair of adjacentrings.

8. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a piston operable inthe cylinder, a rod on the piston extending from an end of the cylinder,a sleeve attached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, the sleeve having a pair ofsubstantially diametrically opposite slots, longitudinally spaced ringson the exterior of the cylinder, and means for limiting relativemovement between the cylinder and piston when the same are in a selectedrelative relationship comprising a U-shaped lock insertable into saidslots to project into the space between a pair of adjacent rings.

9. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a piston operable inthe cylinder, a rod on the piston extending from an end of the cylinder,a sleeveattached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, the sleeve having a pair ofsubstantially diametrically opposite slots, longitudinally spaced ringson the exterior of the cylinder, and means for limiting relativemovement between the cylinder and piston when the same are in a selectedrelative relationship comprising a pair of crossed levers on the sleevefor entering said slots to project into the space between a pair ofadjacent rings.

10. A ram mechanism comprising two parts related for relativelongitudinal movement, one a cylinder, the other a piston operable inthe cylinder, a rod on the pison extending from an end of the cylinder,a sleeve attached to the rod to enclose the projecting portion of thesame and to telescope over the cylinder, the sleeve having a pair oisubstantially diametrically opposite slots, longitudinally spaced ringson the exterior of the cylinder, and means for limiting relativemovement between the cylinder and piston when the same are in a selectedrelative relationship com-, prising a pair of crossed levers on thesleeve for entering said slots to project into the space between a pairof adjacent rings, spring means for urging the levers into the slots,and manually operable means for withdrawing the levers from said space.

VINCENT E. GEREN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,512,837 Evenden Oct. 21, 19241,525 447 Hose Feb. 10, 1925 1,927,078 Weeks Sept. 19, 1933 2,258,825Thompson Oct. 14, 1941 2,362,170 Swaisgood Nov. 7, 1944 2,372,196 GrimeMar. 27, 1945 FOREIGN PATENTS Number Country Date 838,918 Great BritainDec. 1, 1950 507,588 France Jan, 29, 1920

